Assessment of Aqua MODIS and AIRS TIR band L1B radiances using ER-2-based observations during TX-2002

Abstract

During the Terra-Aqua experiment -- 2002 (TX-2002), a NASA ER-2 was used to underfly the EOS Aqua satellite over the Gulf of Mexico for the purpose of gaining insight on the accuracy of MODIS and AIRS thermal infrared (TIR) band radiances. The ER-2 payload included the MODIS Airborne Simulator (MAS) and the Scanning High resolution Interferometer Sounder (SHIS); these instruments have flown previously on the ER-2 for assessing Terra MODIS TIR band radiances. On November 21, 2002, the ER-2 flew directly under the Aqua satellite, with MODIS and AIRS, as it swept over a clear sky region of the Gulf of Mexico. The MAS and SHIS observations were used to simulate the MODIS thermal IR band radiances for the warm (~ 295 K) Gulf of Mexico scene. The results of comparing the simulated MODIS radiances with the MODIS observations show Aqua MODIS TIR bands are performing well. The residuals (MAS - MODIS) in most bands are within or very near specification. The split window 11 and 12 μm band residuals are small and very close to one another at -0.15°C and -0.13°C, respectively. The comparisons suggest that MODIS LWIR CO2 sensitive bands 35 (13.9 μm) and 36 (14.2μm) may be calibrated slightly warm by about 1°C. Early direct comparisons between MODIS and AIRS on Aqua also suggest that the MODIS bands 35 and 36 may be calibrated slightly warm.